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MMI133 > MMI133_Lecture12 > Flashcards

MMI133_Lecture12 Flashcards

1
Q

pathogen

A

microorganism that can cause a disease process

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2
Q

primary pathogens always

A

cause disease - even in healthy immuno-competant individs

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3
Q

opportunistic pathogen

A

microorganism that may cause disease if given the right circumstances

Candida albicans - immunosuppression
Mucor spp - diabetics
Pseudomonas aeruginosa - burns, CF, HIV, + neutropenic cancer patients

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4
Q

pathogenicity

A

ability to cause disease by evading or overcoming the host defences

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5
Q

virulence

A

extent to which the microorganism is pathogenic

how much disease it can cause

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6
Q

virulence factors

A

molecs/structures produced by pathogens that contribute to their pathogenicity or ability to cause disease

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7
Q

virulence factor of Streptococcus pneumoniae

A

capsule
cannot cause disease without capsul

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8
Q

portals of entry

A

how pathogen gains entry to host

mucous membranes
skin
parenteral route via mouth
surgical sites + implants can provide route to bypass these
some have preferred protal of entry + can only cause disease thru specific route

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9
Q

tropism

A

a liking of an organism for a certain cell or tissues

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10
Q

tropism is determined by

A

distribution of cell receptors for microbes
accessibility of correct host cell types
other competing microbes
nut.s for growth
physical + innate difenses at the site of infection + age
permissive environmental condition like pH

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11
Q

some pathogens can

A

remain at site of infection + don’t have to spread thru system to cause disease

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12
Q

exotoxin producing bacteria

A

corynebacterium diphtherieae
vibrio cholerae
clostridium tetani, botulinum, perfringens
bordetella pertussis

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13
Q

first step of infection

A

adherence + binding

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14
Q

pathogens adhere + bind in infection by

A

adhesins/ligands (pathogen structures) recognizing + binding to receptors on host cells

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15
Q

adhesins = ligands

A

structures on pathogens that bind to host receptor in adherence step of infection

most on pathogens are glycoproteins or lipoproteins

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16
Q

receptors

A

strucutres on host cells that adhesins/ligands bind to when pathogen binds to host cell

most are sugars like mannose

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17
Q

factors that help bact evade + penetrate host defenses

A

capsules
cell wall compenents
biofilms
enzymes
invasins
superantigens
toxins
secretion systems
antigenic variation
intra/extracellular growth

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18
Q

capsules

A

glycocalyx = capsule + slime layer etc

initially prevents phagocyte from recognizing + binding to + ingesting bact

many can in right conditions

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19
Q

cell wall compenents

A

fc receptors on microorganisms prevent opsonization

fc’s covered up by cell wall compenents so phagocytes can’t eat them

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20
Q

M protein

A

heat + acid-resistant protein in cell wall that allows attachment of bact to epithelial cells + inhibits phagocytosis

Streptococcus pyogenes

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21
Q

Mycolic acids

A

waxy substance in cell walls make bact resistant to digestion inside phagocyte

Mycobacterium tuberculosis

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22
Q

biofilms

A

united we stand for bact

community of bact surrounded often by shared glycocalyx
reduced antibiotic effectiveness WBC penetration

bad in medical implants

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23
Q

exoenzymes released form bact cells

A

leucocidin - destroys WBC
kinase - breaks down fibrin + dissolves clots formed by body to isolate infection
hemolysin - break down RBC

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24
Q

coagulase

A

clots - converts fibrinogen (soluble in plasma) to fibrin protein strands which clot and can wall bact off from host defeneses

Staphylocuccs aureus

25
Q

collagenase

A

breaks donw collagen CT
clostridium perfringens

26
Q

lecithinase

A

destroy PM’s clostridium perfringens

27
Q

proteases

A

inactivate antibiotics + other body proteins like IgA protease

neisseria gonorrhoeae

28
Q

coagulase test

A

plasma with bact is incubated and there’s soluble fibrinogen in the plasma
after incubation, if it’s positive for coagulase then it will clot bec coagulase will clot the blood, if it doesn’t clot then -, bec it’s not turned to fibrin by coagulase

29
Q

invasins

A

surface proteins on some bact which activate actin - the cytoskeleton eukaryotic cells
rearranges + facilitates bact engulfment into host cell

30
Q

superantigens

A

type 1 exotoxins

protein antigens that stimulate super large immune response

instead of <1% Th cell activation in normal antigens, it causes 20% Th cell activation

unspecific binding to MHC II + TCR
results in excessive cytokine release
immune system works against us

bipass keep to act, not lock and key antigen, but a master key antigen

31
Q

toxins

A

often primary virulence factor
usually proteins that produce fever + cause heart failure, diarrhea, edema or shock
can destroy cells

endotoxin - LPS lipid A - molec contributes to bact structure
exotoxin - incl superantigens - extra protein made by bact to affect cells other than itself

32
Q

endotoxins

A

ONLY G- bact
lipopolysaccharide LPS) + lipid A
heat stable

33
Q

shock

A

life-threatening loss of BP

34
Q

septic shock

A

shock caused by any bact

35
Q

endotoxic shock

A

shock caused by G- bact

36
Q

streptococcus pneumoniae

A

G+ diplococcus

37
Q

exotoxins

A

proteins certain bact make + release into tissues

G+ + G-
genes for exotoxins carried by bacteriophages or plasmids
diphtheria toxin, tetanus toxin

Cytotoxin - cell
neurotoxin - nerves
enterotoxin - intestines

heat labile/sensitive to heat
antitoxin antibodies for neutralization

38
Q

exotoxin-caused diseases

A

botulism
tetanus
gas gangrene
diphtheria
whooping cough
listeriosis
cholera

39
Q

Clostridium botulinum

A

causes flaccid paralysis due to botulism toxin

40
Q

Clostridium tetani

A

causes spastic paralysis = lockjaw, due to tetanus toxin

41
Q

pathogenicity island

A

chromosomal region where the genes are clustered

42
Q

type III apparatus enables

A

a bact cell to inject proteins into a host cell, killing or altering it

43
Q

antigenic variation

A

escaping immune system by changing their antigens
some pathogens change the makeup of their antigens as they replicate/mutate and immune system sees them as new pathogens

creates new antigen by the time host has created antibodies to first one

44
Q

obligate intracellular bacteria

A

can only grow inside of host cells, often in protected vacuole

45
Q

facultative intracellular bacteria

A

can multiply outside host cells, but often use intracellular growth as means of evading host defenses

Bordetella, mycobacterium, Salmonella

46
Q

Hemolysin will

A

not help pathogens avoid immune detection

47
Q

3 methods of horizontal gene transmission

A

conjugation
transduction
transformation

48
Q

conjugation

A

transferral of plasmids containing genes for virulence attributes or antibiotic resistance

49
Q

transduction

A

acquisition of genes for toxin production eg. C. diphtheriae bact via transferral by bacteriophage

50
Q

transformation

A

acquiring gene for toxin, capsule production etc, by absorbing naked DNA from environment arnd bacterium

51
Q

plasmid

A

small circular DNA molecs separated from main bacterial chromosome

encode antimicrobial resistance or virulence factors

52
Q

bacteriophages

A

viruses which infect specific bacteria
transfer genes by transduction

53
Q

what is name for 2 live bacterial cells directly passing DNA betw each other

A

conjugation

54
Q

most effects of viral infections caused by

A

inflammation + activation of immune system producing disease

55
Q

cytopathic effects CPE

A

kiilling or damaging of host cell
diff strains of virus cause diff CPE

56
Q

syncytium formation

A

infected cells fuse to form giant cell with many nuclei
giant virus producing factory
giant cell dies when viruses use up all building material + cause necrosis of tissue
permits viral multiplication without exposing virus to antibodies

57
Q

syncytium

A

mega infected virus-hyjacked cell
virus making factory

58
Q

viral pathogenicity - what can viruses do to cause disease?

A

evade immunity with syncytium + make face MHC I

disrupt cellular life cycle + activity

can cause cancer - induce chromosomal changes in cells oncoviruses, deregulate contact inhibition so cell growth doesn’t stop when runs out of space

59
Q

what is a common thing betw bact + some viruses

A

can replicate intracellularly

MMI133 (16 decks)

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